The bookshelves of Mainz University lecturer Wolfgang Lustig are lined with books on Guarani that could prove useful to football players soon - at least those pitted against the team from Paraguay.
Lustig teaches Guarani, Paraguay's 'secret language'. His students also have excellent contacts to the South American country.
The books include translation aids for Guarani, the native language that Paraguayan footballers also speak.
"The players could use Guaraní as a 'secret language' to hide tactics from others," said literary researcher Lustig.
Guarani is actually anything but secret - whether spoken at home, on the streets or on the football pitch, Guarani is Paraguay's vernacular.
More than 90 percent of the population, or more than four million people, speak a tongue that stems originally from native Indian inhabitants.
According to Lustig, attempts to give the language more meaning have come mainly from abroad. He published his own language guide, which is aimed at development aid workers.
But the 52-year-old also wants to bring his students closer to Guarani.
Language courses are offered only sporadically at Mainz University, but Lustig's seminars about Guarani are a regular feature. "The basics of the tongue are important for those studying Romance languages," said Lustig.
When it comes to social projects, Lustig also gets his students to bang the drum for Paraguay. He has founded a group, which supports the Indian communities in western Paraguay.
"We are supporting school and health projects and help to sell teas and handicrafts," Lustig explained.
"Guarani is the language of the common people and of emotions. Spanish is for official life," the lecturer said. Guarani also enjoys the status of an official language in the South American country.
"Officially, both languages are equal. But Guarani is actually less useful," Lustig said. The reason? "People who speak Guaraní only can't even use it to open a bank account in Paraguay. The language has no link with modern life."
Counting in the language does not go beyond four, and words like hospital and television are not even used, the expert tells his students.
"Of course these words are in the dictionary. But nobody knows them or uses them because Spanish dominates modern life," the professor said.
"The language is virtually never written in public," Lustig says.
The Paraguay expert at the Institute for Romance Language Studies at the Johannes Gutenberg University fears that Guaraní may die out altogether within a few decades.
"The linguistic nutrition of the people comes through the mass media. And the language isn't used there," Lustig told his students.
Nevertheless, the academic and a few of his students too hope that Paraguay's footballers will be able to baffle their opponents with their 'secret language' at the World Cup and spring some surprises as a team.